Photochemical reaction of cyclohexyl phenyl ketone within lyotropic liquid crystals

Lyotropic liquid crystals (LCs) formed by sodium dodecyl sulfate (SDS), n-pentanol, and H₂O at room temperature in their tertiary phase diagram have been explored as a confined medium for the typical photochemical reaction of cyclohexyl phenyl ketone (1), which can lead to either intramolecular hydrogen abstraction product 2 or intermolecular reduction product 3 in isotropic solutions upon irradiation. Studies on the product distributions of ketone 1 in the absence and presence of electron donors in this work demonstrate that LC not only restricts the movement of the substrates and intermediates but also encapsulates the substrates and electron donors together during photoirradiation, thereby giving rise to the formation of intermolecular hydrogen abstraction product 3 with high efficiency. A comparison of the same reaction in SDS micelle reveals that LC provides much better constraint than the micelles. The solution-like LC can be used as a microreactor to direct the reaction pathway of ketone 1 by controlling the viscosity and close contact between substrates and electron donors.